In recent years, a new type of plastic surgery has been introduced wherein fat is removed from within the human body by using a thin metal suction tube that is introduced through a tiny skin incision and repeatedly thrust through the unwanted fat to break up the fat globules. Vacuum is applied when it is desired to remove the loosened fat globules. The medical instrument for performing such an operation comprises a hollow body for holding by the hand. At one end, a suction probe is attached to the body and the other end of the body is connected to a source of vacuum. The probe is used to break the fat globules and then suction is applied to suck the loosened fat globules out of the body. The probing and sucking is repeated until the desired amount of fat is removed. In some cases, the operation will require hours of probing and sucking. In the past, a foot control valve has been used to apply the suction even though medical instruments used in oral surgery, such as those marketed by Lorenz, have had suction control valves associated with a hollow body.